There is no extensive background check, they merely run your name thru CPIC - basically check the police records across Canada/USA for any hits that show a criminal past in North America.
Same check you get if you work at a bank, or any job that requires finger printing!, merely a formality.
A Canadian Passport is not required, As a member of the Commonwealth with your work VISA is all that is required.
You can also check on AvCanada.ca they have a forum where you can monitor the job marked or place your own post.
There are lots and lots of Aussie's working in Vancouver - especially up at Whistler - You'll love BC so enjoy your time and good luck!!!
AVCANADA :::WELCOME:::
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Canada's New Government Proposes to Boost Airport Security with Biometric Technology - Transport Canada
http://www.volunteer.ca/files/PRCBrochureEng.pdf
How to Obtain a Certified Criminal Record Check